American telecommunications giants are selling access to their customers’ location data, leaving them exposed to being tracked by bounty hunters and others, a disturbing report by Motherboard has revealed.

T-Mobile, Sprint, and AT&T are reportedly among the companies whose data is being used to track phone locations, leaving mobile network users exposed without their knowledge.

US telecommunication companies sell user data to aggregator companies who then sell this information in turn to their own customers. The data can then be re-sold on the black market, where it could fall into the hands of criminals, stalkers and others.

Motherboard reporter Joseph Cox paid a bounty hunter to geolocate a target’s T-Mobile phone in his investigation into the location tracking practice. The bounty hunter’s contact was able to track the phone to the correct Queens neighborhood within a few hundred meters of its location. This was done without any hacking or previous knowledge of the owner’s location.

Tracking the target

T-Mobile shared user location data with a data aggregator company called Zumigo, which shares information with another company called Microbilt. Microbilt sells phone geolocation services to a number of private industries, like property managers, bail bondsmen and roadside assistance, company documents and sources revealed to Motherboard.'